你自己說是“八卦”，現在又serious啦？

這樣出爾反爾，可做不了一個好證人啊。

Seriously, you can try to make a police report.  I am just not sure what you have to say.  Is it about the incident in China or an incident happened during a phone call between the US person and Chinese person?  You have to have who, when, where, what, how. 

Since I am not sure the 5W's, proceed at your own risk.